[openstack-dev] [os-brick][nova][cinder] os-brick/privsep change is done and awaiting your review

Duncan Thomas duncan.thomas at gmail.com
Wed Feb 24 13:05:43 UTC 2016


My (negative) feedback is on the review - I'm really not sure that this
matches what I understood the vision of privsep to be at all.

- If this is the vision / the new vision then I think it is majorly flawed.

- If it is skipping the vision in the name of expediency of implementation,
then I think it has gone too far in that direction and we've better off
holding off one more cycle and putting it in next cycle instead with a
touch more purity of vision.

Apologies since you've clearly put work into it, and I should have provided
such feedback earlier.


On 24 February 2016 at 14:59, Michał Dulko <michal.dulko at intel.com> wrote:

> On 02/24/2016 04:51 AM, Angus Lees wrote:
> > Re: https://review.openstack.org/#/c/277224
> >
> > Most of the various required changes have flushed out by now, and this
> > change now passes the dsvm-full integration tests(*).
> >
> > (*) well, the experimental job anyway.  It still relies on a
> > merged-but-not-yet-released change in oslo.privsep so gate + 3rd party
> > won't pass until that happens.
> >
> > What?
> > This change replaces os-brick's use of rootwrap with a quick+dirty
> > privsep-based drop-in replacement.  Privsep doesn't actually provide
> > much security isolation when used in this way, but it *does* now run
> > commands with CAP_SYS_ADMIN (still uid=0/gid=0) rather than full root
> > superpowers.  The big win from a practical point of view is that it
> > also means os-brick's rootwrap filters file is essentially deleted and
> > no longer has to be manually merged with downstream projects.
> >
> > Code changes required in nova/cinder:
> > There is one change each to nova+cinder to add the relevant
> > privsep-helper command to rootwrap filters, and a devstack change to
> > add a nova.conf/cinder.conf setting.  That's it - this is otherwise a
> > backwards/forwards compatible change for nova+cinder.
> >
> > Deployment changes required in nova/cinder:
> > A new "privsep_rootwrap.helper_command" needs to be defined in
> > nova/cinder.conf (default is something sensible using sudo), and
> > rootwrap filters or sudoers updated depending on the exact command
> > chosen.  Be aware that any commands will now be run with CAP_SYS_ADMIN
> > (only), and if that's insufficient for your hardware/drivers it can be
> > tweaked with other oslo_config options.
> >
> > Risks:
> > The end-result is still just running the same commands as before, via
> > a different path - so there's not a lot of adventurousness here.  The
> > big behavioural change is CAP_SYS_ADMIN, and (as highlighted above)
> > it's conceivable that the driver for some exotic os-brick/cinder
> > hardware out there wants something more than that.
> >
> > Work remaining:
> > - global-requirements change needed (for os-brick) once the latest
> > oslo.privsep release is made
> > - cinder/nova/devstack changes need to be merged
> > - after the above, the os-brick gate integration jobs will be able to
> > pass, and it can be merged
> > - If we want to *force* the new version of os-brick, we then need an
> > appropriate global-requirements os-brick bump
> > - Documentation, release notes, etc
> >
> > I'll continue chewing through those remaining work items, but
> > essentially this is now in your combined hands to prioritise for
> > mitaka as you deem appropriate.
> >
> >  - Gus
> >
>
> It seems too me that risks are higher than advantages. Moreover final
> release for libraries like os.brick should happen in just 2 days and I
> don't believe we have time to get every part of the job merged given how
> long TODO list is.
>
> Just my $0.02.
>
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-- 
-- 
Duncan Thomas
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